Compact slurry preparation system for oil sand

Abstract

Staged crushing combined with water addition and mixing is practiced at the mine site to prepare an oil sand slurry ready for hydrotransport. More particularly, as-mined oil sand is crushed to conveyable size (e.g. —24″) using a mobile crusher. The pre-crushed ore product is conveyed to a dry ore surge bin. Ore is withdrawn from the bin and elevated to the upper end of a slurry preparation tower having downwardly aligned process components to enable gravity feed. The ore is further crushed in stages to pumpable size (e.g. —4″) by a stack of crushers and water is added during comminution. The ore and water are mixed in a mixing box and delivered to a pump box. The surge bin and tower are relocatable. Screening and oversize reject treatment have been eliminated to achieve compactness and enable relocatability.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a system for forming an aqueous slurry of oil sand, so that the slurry is suitable for hydrotransport. The system has process and apparatus aspects.BACKGROUND OF THE INVENTION[0002]Over the past 30 years, as-mined oil sand containing bitumen has been slurried and conditioned at applicants' facilities in two different ways.[0003]In the earlier process, the excavated or ‘as-mined’ oil sand was comminute to conveyable size (e.g. −24 inches) with a roll crusher at the mine site and transported on belt conveyors to a central bitumen extraction plant. Here the pre-crushed oil sand was fed into the front end of a horizontal rotating tumbler. Hot water (e.g. 95° C.) was also added, together with a small amount of caustic. The resulting slurry was cascaded as it advanced through the large tumbler over a period of several minutes. Steam was sparged into the slurry to ensure that it was at a temperature of about 80° C. when it exited...

AI Technical Summary

Benefits of technology

"The present invention provides a method for producing a pumpable oil sand slurry at a mine site by using multiple stages of size reduction, combined with process water addition and mixing. This eliminates the need for screening and reject treatment during slurry preparation. The process involves comminuting the oil sand to conveyable size, delivering it to a surge bin, removing it from the surge bin and delivering it to an elevated point, preparing a pumpable slurry by sequential downwardly descending comminution stages, adding heated water to the oil sand, and mixing it to form the pumpable slurry. The slurry is then discharged into a pump box for feeding to a pump and pipeline system. This method simplifies the process of producing a pumpable oil sand slurry and reduces the need for screening and reject treatment."

Problems solved by technology

In addition the belt conveyors were expensive and difficult to operate.

There are some problems associated with the Aurora facility.

The components do not lend themselves to being relocatable.

However, this leads to the production of oversize rejects and the need for equipment to treat the rejects for recycling;These oversize rejects can amount to 3% of the original oil sand.

There is a bitumen loss associated with the final rejects and it is expensive to haul them to a disposal area; andThe dry ore surge bin is four sided, with twin bottom outlets feeding the apron feeder.

A frequently encountered problem at Aurora is that tacky bitumen-rich oil sand has a tendency to plug the bin outlets and it is then necessary to apply air permeation to assist flow.

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